In current container handling equipment, there is always an about 60 meter long electric cable hanging between a crane and a spreader used to supply power and for communication. During the processes of lifting and lowering, the hanging cable should be able to be effectively pulled out from or pulled back in a cable basket or a cable reel. Once the lifting speed exceeds a certain value or a high wind comes, the hanging cable may not be pulled out or back smoothly. Thus the cable may drop out of the cable basket, or may be hooked and even broken, which will influence the performance of the crane and its all weather operation. What is more, a hanging cable is very expensive, if broken, it would be costly to replace it with a new one.
If a cable reel is used to pull out or back a cable, a complicated electronic and mechanic drive system has to be installed on a trolley of the crane, which would result in an increased failure rate and maintenance for the whole machine. Besides, in current spreaders for lifting goods containers, a hydraulic power station, used as a power source of a spreader is normally driven by an electric motor, and all the pulleys of the pulley sets on the headblock of the spreader rotate idly with the rotational energy wasted.